Summary

We show that the most interesting type of farming for biodiversity depends on the equilibrium on agricultural markets. All other things being equal, when demand reacts to prices and when extensive farming has higher production costs, this type of farming may allow a higher level of biodiversity than intensive farming if the relation between biodiversity and yield does not have a very high degree of convexity. This extensive farming is detrimental to consumers when their surplus is evaluated restrictively as increasing with quantities consumed and decreasing with higher prices. Its effect on agricultural producers is indeterminate. It does not have a simple effect on food security.